1. Field of the Invention
The present invention relates to power amplifying device, and in particular, to power amplifying device for millimeter and micrometer wave bands.
2. Background Art
In Japanese Unexamined Patent Publication No. 2002-353745, a radio frequency power amplifying device for millimeter and micrometer wave bands is described, which comprises a stabilizing circuit disposed near the transistor in order to allow stable operation.
When the stabilization circuit is disposed in the power amplifying device, there is a possibility not to be able to stabilize enough if the change of the characteristic of the transistor is not considered. That is, to attain satisfactory stabilization, it is necessary to take into consideration the changes of characteristics of the transistor. However, there exists a trade-off relation between the stability and the amplifying capability. Particularly, in the millimeter wave band, if no characteristics margin is given to the transistor, designing the stabilizing circuit so as to secure stability regardless of changes of the characteristics of the transistor is likely to make useless much of its potential as an amplifying device.